El rol de la evapotranspiración en la geohidrología del humedal de la Planicie Costera de Ajó (Provincia de Buenos Aires)

The wetland of the Ajó coastal plain in the Province of Buenos Aires shows different hydrological characteristics depending on whether the sector is influenced by the tidal flow or not. The aim of this work is to assess the role of evapotranspiration in the geohydrological behaviour of the sector of the wetland which remains out of the tidal cycle. Landsat visible and infrared (VNIR) satellite images, rainfall, temperature, chemical data (major ions and isotopes) and water level of surface and groundwater were analysed. The study includes a wet and a dry period between September 2005 and March 2006. A decrease in the flooded area, a deepening of the water table and an increase in the salinity of the surface water and groundwater were observed in the transition of the wet period to the dry period. The water budgets and the chloride and isotope contents indicate the relevance of evapotranspiration, which is demonstrated by the hydrodynamic and hydrochemical conditions of the wetland.